1. Field of the Invention
The instant disclosure relates to a method of positioning; in particular, to a method of single-point distance measurement and an electronic apparatus using the same.
2. Description of Related Art
Global Position System (GPS) has been widely used not only in military but also in daily life. The common implementation is target positioning and navigation. Conventional positioning apparatus (or navigation apparatus) employs GPS as the core functionality. GPS combines the advantages of satellites and wireless communication, such that precise information including position, speed or time can be provided swiftly.
GPS heavily relies on the collaboration between satellites, positioning apparatus and navigation software. However, it is very likely satellite signal is not available or weak because of the positioning apparatus is shielded by buildings. This may happen, for example, in the airport, among skyscrapers, in the underground or tunnels. Positioning cannot be accurately executed without the reception of satellite signals. Therefore, whenever GPS location information is needed, a user has to be outdoor so as to read GPS location information from satellites. The inability of obtaining GPS location information regardless where a user is causes certain inconvenience.
Cell tower signals have been used in positioning with the absence of a valid GPS location. For example, a mobile phone detects the signal strength from the surrounding cell towers. Accordingly, the approximate distance between the mobile phone and the cell towers is obtained. Meanwhile, the exact location of each cell tower can be identified through their code, and the mobile phone position can be estimated. The radio signal is capable of penetrating buildings, such that a portable device can be positioned indoor. Nevertheless, the location information is less accurate because the cell towers may be kilometers away from one another. In addition, radio signals attenuate due to building blockage. As a result, the accuracy of cell tower positioning is compromised.
On the other hand, Wireless Fidelity (Wi-Fi) system is widely used especially in urban area, and the number of wireless routers increases dramatically due to individual or industrial establishment. Wi-Fi Positioning System (WPS) takes the advantage of the high access point density and broad coverage and seeks the closer hot spots. In this regard, a speculative location of an application can be obtained from nearby access points.
Please refer to FIG. 1 showing a schematic diagram of conventional WPS. The access points are designated as 11, 12 and 13 and an electronic apparatus 101 (e.g. a mobile phone, tablet or the like). Firstly, the electronic apparatus 101 detects the media access control address (MAC) of the nearby access points 11-13 and the signal strength thereof. Then, the location information can be obtained by cross examination and calculation. However, WPS is rather limited to an area having higher density of the access points.